Global Warming

  2010 AUG 16 - (VerticalNews.com) -- "We extend the theory of climate feedbacks to include atmospheric chemistry. A change in temperature caused by a radiative forcing will include, in general, a contribution from the chemical change that is fed back into the climate system; likewise, the change in atmospheric burdens caused by a chemical forcing will include a contribution from the associated climate change that is fed back into the chemical system," investigators in Ispra, Italy report ...read more

  2010 AUG 16 - (VerticalNews.com) -- "Aerosol indirect effects (AIE) are a principal source of uncertainty in future climate predictions. The present study investigates the equilibrium response of the climate system to present-day and future AIE using the general circulation model (GCM), Goddard Institute for Space Studies (GISS) III," scientists in the United States report.

  "A diagnostic formulation correlating cloud droplet number concentration (N-c) with concentrations of aerosol soluble ions is developed as a basis for the calculation. Explicit dependence on Nc is introduced in the treatments of liquid-phase stratiform clouds in GISS III. The model is able to reproduce the general patterns of present-day cloud frequency, droplet size, and radiative balance observed by CloudSat, Moderate Resolution Imaging Spectroradiometer, and Earth Radiation Budget Experiment. For perturbations of N-c from preindustrial to present day, a net AIE forcing of -1.67 W m(-2) is estimated, with a global mean surface cooling of 1.12 K, precipitation reduction of 3.36%, a southward shift of the Intertropical Convergence Zone, and a hydrological sensitivity of + 3.00% K-1. For estimated perturbations of N-c from present day to year 2100, a net AIE forcing of -0.58 W m(-2), a surface cooling of 0.47 K, and a decrease in precipitation of 1.7% are predicted. Sensitivity calculations show that the assumption of a background minimum N-c value has more significant effects on AIE forcing in the future than on that in present day," wrote W.T. Chen and colleagues, California Institute of Technology, Institute of Technology ...read more

  2010 JUN 28 - (VerticalNews.com) -- "Polar mesospheric clouds (PMC) routinely form in the cold summer mesopause region when water vapor condenses to form ice. We use a three-dimensional chemistry-climate model based on the Whole-Atmosphere Community Climate Model (WACCM) with sectional microphysics from the Community Aerosol and Radiation Model for Atmospheres (CARMA) to study the distribution and characteristics of PMCs formed by heterogeneous nucleation of water vapor onto meteoric smoke particles," scientists in the United States report ...read more